1. Field of the Invention
The present invention relates to a fuel hose for transportation or the like of fuel for automobiles and the like such as gasoline, alcohol-containing gasoline, diesel fuel, FAME (fatty acid methyl ester)-containing diesel fuel, a synthetic fuel-containing diesel fuel (such as GTL (Gas to Liquid)), CNG (Compressed Natural Gas) or LPG (Liquefied Petroleum Gas).
2. Description of the Art
With growing worldwide awareness of environmental issues, the control of the amount of fuel permeation from an automotive fuel hose and the like has been enhanced. Particularly in North America, stringent regulations against fuel permeation are recently coming into effect. Under such a situations a fuel hose has been proposed which has a three-layer structure including an inner layer composed of acrylonitrile-butadiene rubber (NBR), an intermediate layer composed of a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer (THV) and an outer layer composed of NBR-PVC, or which has a four-layer structure including the same inner layer, the same intermediate layer, an outer layer composed of NBR and an outermost layer composed of chlorosulfonated polyethylene rubber (CSM).
However, the layer made of NBR does not adhere well to the layer made of THV. Therefore, a fuel hose having improved interlaminar adhesion between the NBR layer and the THV layer by adding 1,8-diazabicyclo[5.4.0]undecene-7 salt (DBU salt) into the NBR layer has been proposed (see Japanese Unexamined Patent Publication No. 8-169085 (19961).
However, NBR employed as a material for forming the fuel hose as described in the Publication is inferior to a blend of acrylonitrile-butadiene rubber and polyvinyl chloride (NBR-PVC) in fuel-permeation resistance, ozone resistance, sour-gasoline resistance and the like, so that the resulting hose has lower product reliability. Therefore, it is considered that the NBR is replaced by NBR-PVC, excellent in fuel-permeation resistance, ozone resistance, sour-gasoline resistance and the like as a hose material, and also interlaminar adhesion between the NBR-PVC layer and the THV layer is improved by adding DBU salt into the NBR-PVC layer, as mentioned above. However, even if DBU salt is added to the NBR-PVC layer, the interlaminar adhesion between the NBR-PVC layer and the THV layer is not so much improved to the extent that the case where DBU salt is added to the NBR layer.
In view of the foregoing, it is an object of the present invention to provide a fuel hose excellent in fuel permeation resistance and interlaminar adhesion.